In U.S. Pat. Nos. 3,116,557 and 3,279,070 there are disclosed methods for laying a pipeline with the use of a collimated light (laser) beam which is aligned along a preselected path for the pipeline. The last pipe in the line has a target coupled to the end. The pipe is moved until the target is aligned with the collimated beam and the pipe is then fixed in place. The pipeline is extended by inserting one end of another pipe into the end of the aligned pipe and aligning the other end with a target in the same manner as the previous pipe. The process is repeated until the pipeline has been extended the desired length.
As a general rule, a laser light source is positioned in a manhole and the beam is projected along the path of a pipeline. If the pipeline will carry fluids into the manhole, then the beam is elevated. Likewise, if the pipeline will carry fluids out of the manhole, then the beam is downwardly inclined. Targets are generally designed for use in pipe having a range of internal diameters. Thus, use of a target requires that it be precision adjusted so that the cross-hairs of that target will be aligned with the longitudinal axis of the pipe.
One problem associated with the laying of a pipeline is the entry into the pipeline of dirt, gravel and trash. Typically, this foreign material must be cleaned out of the pipeline before it can be put into use. This can be a costly and time-consuming process. Certainly, rather than cleaning the interior of an installed pipeline, it would be far better if the foreign material is prevented from entering the pipeline in the first place.